Electrically-heated steam boiler



De@ s, 1925.

vc. w. CAMPBELL ELECTRIGALLY HEATED STEAM BOILER Filed Sept. 15. 1924 Patented Dec. 8, 1925.

UNITED STATES PATENT OFFICE.

CARLETON W. CAMPBELL, OF DENVER, COLORADO, ASSIG-NOR, BY MESNE ASSIGN- MENTS, T0 MOLL MANUFACTURING- COMRANY, A CORPORATION OF COLORADO.

ELECTRICALLY-HEATED STEAM BOILER.

Application filed September 15, 1924. Serial N'o. 737,820.

To all 'whom it may concern.'

Be it known that I, CARLETON W. CAMP` BELL, a citizen of the United States of America, residing at Denver, in the county of Denver and State of Colorado, have Ainvented certain new and useful Improvements in Electrically-Heated Steam Boilers, of which the following is a specication.

This invention relates to steam boilers, more particularly o-f the type as used in connection with tire repair and vulcanizing outits. y

The principal object of the invention is to so construct a boiler of this type that electricity can be efliciently used as a heating agent.

Another object is to provide automatically regulated heat control in the boiler, the control being actuated by the boiler pressure.

A further object is to construct a heating unit for a boiler of this type which will be highly efficient and which can be readily manufactured and renewed.

A still further object is to so place the heating units in the boiler that all of the heat radiated therefrom will be efficiently used and to so insulate the boiler that wastage of heat will be substantially eliminated.

Other objects and advantages reside in the detail construction of the invention, which result in simplicity, economy, and efliciency, and which will become more apparent from the following description.

In the following 'detailed description of the invention, reference is had to the accompanying drawing which forms a part hereof. Like numerals refer to like parts in all views of the drawing and throughout the description.

In the drawing:

Fig. 1 is a side elevation of my impro-ved boiler, partly in section to disclose the interior construction.

Fig. 2 is a horizontal cross section taken on the line 2 2, Fig. 1.

Fig. 3 is a detail view of the novel 'electrical heating element employed in my invention.

The invention comprises a steam tight water container 10 supported on suitable legs 11. The container 10 is provided with the usual equipment, such as; a filler plug 12, air cock 13, safety valve 14, water gauge 15 and steam pressure gauge 16. The pressure gauge 16, however, is constructed to act as an electric circuit breaker, controlled by the pressure in the container 10. The details and operation of the gauge 16 are more fully illustrated and described in a co-pending application for patent on an improvement in vulcanizing machines, Serial No. 709,425, filed April 28, 1924, by J. A. Cross, and which has been assigned to the assignee of the present invention.

The `extremities of the container 10 are closed by suitable heads or caps 17. Beaded into the caps 17 and passing longitudinally through the container 10, are a series of tubes 18, in each of which is carried a novel electrical heating unit 19. The heating units 19 extend upward in the tubes 18 from the bottom of the container 10 to a point just below the normal water line1 indicated at 20.

Completely surrounding, and extending above and below the container 10 is a jacket 21 covered by a lid 22. The entire space between the container 10 and the jacket 2l is filled with heat insulating material 23, which also fills the upper extremities of the tubes 18, as shown at 24. For this material I pre fer to employ a cement formed of asbestos liber and fire clay, since such a composition readily retains its shape after setting. Any other suitable insulator may be employed, however. The tubes 18 are first filled with insulating material; the entire jacket is then inverted and lled flush with the bottom and allowed to set.

The construction of the heating units 19 is believed to be new and novel. They are constructed by casting a cylinder 25 of the above described cement around a central metal bar 26. One extremity of the bar 26.

is bent as shown at 27 and provided with an electrical binding post 28, the other extremity carrying a similar binding post 29. Secured at the bent extremity of the bar 26, but insulated therefrom by suitable electric insulation 30, is an L shaped bar 31 which carries binding posts 32 and 33 at its inner and outer extremities respectively.

An electrical resistance wire 34 such as nichrome ribbon is now wound around the cylinder 25 in spaced coils and secured at its extremities to the binding posts 29 and 32. Caps 35 of a relatively hard, refractory, insulating material are now cast on the extremities of the cylinder 25.

The cylinder 25 with its coil of resistance wire 34 is of less diameter than the interior diameter of the tubes 18. Therefore, a space is left between the coil and the tube Wall which prevents injury to the coil and short circuiting thereof.

The coil is noW covered With a thin layer 36 of insulating` cement which fills the interstices between the coils and prevents adjacent coils from coming into contact.

After the coils 19 are in place in the tubes 18, the binding posts 28 and 33 of all the coils are connected in parallel With an electrical conductor 87. The coil connections are all cast into the insulating' material Q3 so that they cannot be disturbed or injured. The conductor 37 receives its current from a main conductor 3S, the flow being controlled by the action of the circuit breaker in the gauge 16. i

Electricity, in most communities, is fthe most expensive of the heating' mediums. TVith the use of the applicants device, however, electrical heat has been made the most economical of heating mediums, since the use 4of the heatingl element is immediately discontinued when the temperature of the water has reached tliedesired degree-there is no Waste in over heating; the electric heating element is completely surrounded by the element to be heated so that all heat developed must do useful Work; and substantially, all radiation of heat by the heated element is prevented through the noval insu- Za` ing construction.

The caps 35 may be cast the exact diameter of the interior of the tubes 18,v or may be cast slightly larger and machined down to the proper diameter to it snugly into the tubes. The latter method is preferred by the applicant.

The boiler or container can be conveniently manufactured from a length of standard Wrought iron pipe closed at its extremities by standard cast iron pipe caps 17 threaded thereon.

While a specific form of the improvement has been described and illustrated herein, it is desired and'understood that the saine may be varied, within the scope of the appended claim, Without departing from the spirit of the invention.

Having thus described the invention, what I claim vand desire secured by LJtters Patent is In an electrically heated steam boiler a vertically arranged pressure container; bands surrounding said container, Ylegs secured to said bands and arranged to support said boiler, a jacket `surrounding and spaced .from the boiler, said jacket being open at its lower extremity and closed at its upper extremity, and heat insulating material filling the space between s aid jacket and said container.

In testimony whereof, I my signature.

CARLETON 1V. CAMPBELL. 

